“How long do teeth last after a root canal?”

After root canal therapy, there is no definitive tome for a tooth to last. It is important, in most cases ti have a cap or crown done to help extend the life of the tooth.

Well done root canal treatment has a 98% chance tooth will stay lifetime. Crown is a necessary after procedure.

It all depends. Every case is different. If the root canal was done well and you properly restored it afterward and if you take immaculate care of it with proper brushing and flossing, no accidents, no grinding teeth etc., it can potentially last a lifetime. Note: a lousy, poor root canal will
last a lifetime if you (god forbid) get killed in a car accident on your way home, but if you live to be 200 years old, it probably won't. Honestly, there is no way to know how long it will last. If you have a good endodontist and good restorative dentist, I would expect it to last.If they didn't last, no one would bother to do it. Good Luck

You have not provided enough information to determine how long it will last. It depends on many factors, but if the tooth is healthy, it should last for many years.